tools/libxl: fix socket display error for CMT

tools/libxl: fix socket display error for CMT

When displaying the CMT information for all the sockets, we assume socket
number is continuous. This is not true in the hotplug case. For instance,
when the 3rd socket is plugged out on a 4-socket system, the available
sockets numbers are 1,2,4 but current we will display the CMT
information for socket 1,2,3.

The fix is getting the socket bitmap for all the sockets on the system
first and then displaying CMT information for_each_set_bit in that bitmap.

Signed-off-by: Chao Peng <chao.p.peng@linux.intel.com>
Acked-by: Wei Liu <wei.liu2@citrix.com>
Reviewed-by: Dario Faggioli <dario.faggioli@citrix.com>